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Frost, Ray L. and Cheng, Hongfei and Yang, Jing and Liu, Qinfu and Zhang, Jinshan (2010) Delamination of kaolinite - potassium acetate intercalates by ball-milling. Journal of Colloid and Interface Science, 348(2). pp. 355-359.

Copyright 2010 Elsevier

1

Delamination of kaolinite–potassium acetate intercalates by ball-milling 1 2 3

Hongfei Cheng a,b,c, Qinfu Liu a, Jinshan Zhang b, 4

Jing Yang c and Ray L. Frost c 5 6

a School of Geoscience and Surveying Engineering, China University of Mining & 7

Technology, Beijing 100083, China 8

9

b School of Mining Engineering, Inner Mongolia University of Science & Technology, 10

Baotou 014010, China 11

12

c Chemistry Discipline, Faculty of Science and Technology, Queensland University of 13

Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001, Australia 14

15 16 Corresponding Author: 17 18 Ray L. Frost 19 P +61 7 3138 2407 20 M: +61 7 414 84 2407 21 F: +61 7 3138 1804 22 E: r.frost@qut.edu.au23

Author for correspondence (r.frost@qut.edu.au) P: +61 7 3138 2407 F: +61 7 3138 1804

2

Delamination of kaolinite–potassium acetate intercalates by ball-milling 24 25 26

Hongfei Cheng a,b,c, Qinfu Liu a, Jinshan Zhang b, 27

Jing Yang c and Ray L. Frost c 28 29

a School of Geoscience and Surveying Engineering, China University of Mining & Technology, Beijing 30

100083, China 31

32

b School of Mining Engineering, Inner Mongolia University of Science & Technology, Baotou 014010, 33

China 34

35

c Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 36

George Street, GPO Box 2434, Brisbane, Queensland 4001, Australia 37

38

Abstract: 39

Structural changes in intercalated kaolinite after wet ball-milling were examined by 40

scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area 41

(SSA) and Fourier Transform Infrared spectroscopy (FTIR). The X-ray diffraction pattern 42

at room temperature indicated that the intercalation of potassium acetate into kaolinite 43

causes an increase of the basal spacing from 0.718 to 1.42 nm, and with the particle size 44

reduction, the surface area increased sharply with the intercalation and delamination by 45

ball-milling. The wet ball-milling kaolinite after intercalation did not change the 46

structural order, and the particulates have high aspect ratio according SEM images. 47

48

Author for correspondence (r.frost@qut.edu.au) P: +61 7 3138 2407 F: +61 7 3138 1804

3

Keywords: Kaolinite; Potassium acetate; Intercalation; Delamination; Particle size 49

4

1. Introduction 50

Kaolinite has a wide variety of applications in industry, particularly as paper filler 51

and coating pigment [1-6]. It is used as an extender in aqueous based paints and inks, a 52

functional additive in polymers and is the major component in ceramics [7-9]. Kaolinite 53

is an inexpensive additive which is able to form stable dispersions and to improve the 54

properties of the material. More recently, this mineral has been found with increasing 55

usage in other applications such as a petroleum cracking catalyst, and a filler in adhesives 56

and plastics [10]. Properties of kaolinite, particularly important for industrial applications, 57

are particle size distribution, particle shape, structural order-disorder and crystallinity, 58

specific surface area and whiteness [5]. These properties can be enhanced with several 59

treatments such as dry-grinding, intercalation and delamination/exfoliation [9, 11, 12]. 60

61

Lately, some methods for intercalation of kaolinite, in which the interlayer space the 62

layered kaolinite particles were intercalated with small molecules such as urea, potassium 63

acetate, dimethylsulphoxide and so on [13-16]. Meanwhile, delamination of kaolinite is 64

an important industrial procedure, which influences the rheological properties of 65

dispersions used in the ceramic industry, the coating properties of the kaolinite used in the 66

paper industry and gas barrier properties of rubber [17]. The delamination/exfoliation can 67

increase the usability of kaolinite reserves by decreasing the particle size and therefore 68

increasing the specific surface area (SSA) of kaolinite. 69

70

In the past few years, great interest has been expressed in research to increase the 71

specific surface area [3, 17-21]. This surface reactivity can be enhanced through particle 72

5

size reduction, which traditionally can be achieved by grinding (either wet or dry) [3, 22]. 73

Often mechanically ground clay minerals are frequently used in industry. Moreover, an 74

innovative technique for decreasing the particle size of clay minerals has been proposed. 75

The previous researches reported the structural degradation of kaolinite is observed, the 76

morphology of kaolinite is damaged and the ratio of the diameter to thickness is very low 77

by the mechanochemical treatment [23]. It is reported that delamination after 78

intercalation was an effective method for reducing the particle-size of kaolinite to the 79

micronic range, while the crystalline structure and lamellar morphology are still retained 80

[3, 11]. In this work, the effect of intercalation and ball-milling on kaolinite is extensively 81

studied. The Scanning electron microscopy (SEM), X-ray diffraction (XRD), Specific 82

surface area and infrared spectroscopy (IR) are used to investigate the changes in the 83

particle-size, crystallinity, and morphology of kaolinite. 84

85

2. Experimental methods 86

2.1 Materials 87

The sample used in this study was the natural kaolinite from Zhangjiakou, Hebei 88

province of China, with particle size of 45 μm. Its chemical composition in wt% is SiO2 89

44.64, Al2O3 38.05, Fe2O3 0.22, MgO 0.06, CaO 0.11, Na2O 0.27, K2O 0.08, TiO2 1.13, 90

P2O5 0.13, MnO 0.002, loss on ignition 15.06. The major mineral component is well 91

ordered kaolinite (95 wt %) with a Hinckley index of 1.31. The potassium acetate (A.R.) 92

was obtained from the Beijing Chemical Reagents Company, China. 93

94

2.2 Samples preparation 95

The potassium acetate (KAc) intercalated compound was prepared by adding 1.05 96

6

kg of kaolinite into 2.45 Kg of KAc solution at a mass percentage concentration of 30 %, 97

stirring for 10 min. After aging for 24 h, a GF-1100 type machine, filled with zircon balls 98

(zirconium dioxide ca. 60 % and silicon dioxide ca. 40% by mass) for multi-purpose 99

high-speed dispersion, was used to grind the KAc intercalated kaolinite slurry for 2h at 100

room temperature. This machine was purchased from Jiangyin Shuangye Machinery 101

Equipment CO. Ltd. The diameter of zircon balls is from 0.8 to 1.2 mm. The zircon balls 102

and the ground slurry were separated by a mesh, and the delaminated kaolinite was 103

recovered by filtration from the ground slurry. A comparative study was taken on the 104

delamination kaolinite without intercalation. Kaolinite slurry without intercalation was 105

obtained from kaolinite and water with a ratio of 1:3. The slurry was aged 24 h, and then 106

ground by zircon balls and recovered by the same process mention above. 107

The samples were allowed to dry at room temperature before the SEM, XRD and 108

FT-IR analysis. 109

110

2.3 Characterization 111

The morphology of kaolinite particles was observed by using a scanning electron 112

microscope (SEM), Hitachi S-4800. Samples were coated with a gold/palladium film and 113

the SEM-images were obtained using a secondary electron detector. The powder X-ray 114

diffraction（XRD）analysis was performed using a Japan Rigaku D/max-rA X-ray 115

diffractometer (40 kV, 100 mA) with Cu (λ=1.54178 Å) irradiation at the scanning rate of 116

2 °/min in the 2θ range of 2.6-50 °. The Specific Surface Area (SSA) values were 117

obtained with an automatic system (Model No. 2200 A, Micromeritics Instrument Corp., 118

Norcross, GA) at liquid-nitrogen temperature, using the BET method. Nitrogen was used 119

7

as the adsorbate. Before measurement, the samples were pre-heated at 80 °C under 120

nitrogen for ca. 24 h. The specific surface area was calculated by the BET equation and 121

the total pore volumes were evaluated from nitrogen uptake at relative pressure of ca. 122

0.99. The particle size distribution was determined by low angle laser light scattering 123

(Lalls, Mastersizer Model, Malvern). The measurements were performed at 25 °C on 124

dispersions of about 10 mg of samples in 50 ml of distilled water. The delamination 125

kaolinite after intercalation and the kaolinite only by ball milling were dispersed using 126

ultrasound bath. Fourier transform infrared (FT-IR) spectroscopic analysis was 127

undertaken using a NICOLET 750 SX spectrometer. FT-IR spectra between 500 and 4000 128

cm-1 were obtained. The samples were prepared at KBr pellets (ca. 2 % by mass in KBr). 129

130

3. Results and discussion 131

3.1 X-ray diffraction 132

133

Figure 1 the XRD patterns of (a) original kaolinite, (b) kaolinite intercalated by KAc, (c) kaolinite 134

ball-milling after intercalation 135

136

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Fig. 1 shows the XRD patters of original kaolinite, kaolinite intercalation compound 137

with KAc and the delamination kaolinite. The XRD pattern of kaolinite intercalation 138

compound shows a large difference from the original untreated kaolinite because of the 139

KAc intercalation. The effect of intercalation causes a decrease in the position of the (001) 140

reflection. The effect of ball-milling causes the loss of the intensity at 1.42 nm and after 2 141

h of milling, no intensity remains in this peak. The intensity decrease of the (001) 142

reflection shows that the kaolinite layers are exfoliated and delaminated. The intercalation 143

caused the destruction of the hydrogen bonding between the kaolinite layers [24]. 144

A previous study reported the method of intercalation and delamination/exfoliation 145

treatment of kaolinite induces the structure degradation of kaolinite [25]. The degree of 146

structural order/disorder of the kaolinite samples can be estimated by XRD. It is reported 147

that an increase of the structural disorder caused an obvious weakening of reflections 11l 148

and 02l (2θ between 17 and 27 °), which were replaced by a broad peak of scattering with 149

weak modulations [14, 26, 27]. However, in this study, no broad peak was found in the 150

pattern of kaolinite intercalation compound; instead, the reflections 022, 13 0, 131, 003, 151

13 1 and 113 can be found in the pattern of the delaminated kaolinite, which suggests 152

that the well crystallized kaolinite almost did not undergo structural degradation after 153

intercalation and ball-milling. The Hinckley index of the samples is shown in Table 1. 154

155

3.2 Scanning electron microscopy (SEM) 156

Fig. 2 displays the SEM images of the original kaolinite, the intercalated kaolinite 157

and the ball milling samples without or with intercalation. The morphology of kaolinite 158

(Fig.2a) indicates book-like structures. The distance of adjacent layers is expanded after 159

9

intercalated by KAc (Fig.2b). The reduction of particle size of kaolinite by ball milling 160

after intercalation is evident in the SEM imagines (Fig. 2d). It is possible to verify in Fig. 161

2d that the book-like structured kaolinite has been delaminated and the individual 162

particles are randomly distributed without forming apparent aggregation. The particles of 163

the ball milled kaolinite with intercalation are less than 2 m, forming a layered 164

morphology with individual platelets. 165

166

167

Figure 2 The SEM images of (a) original kaolinite, (b) kaolinite intercalated by potassium acetate, (c) 168

kaolinite ball-milling without intercalation and (d) kaolin by intercalation and ball-milling 169

170

Previous studies suggest that the morphology of kaolinite is thick stacks and the 171

sheet-type structure of the kaolinite is retained after mechanochemical treatment [28, 29]. 172

10

A comparison of Fig.2c and d gives new discovery that not only the particle size of 173

kaolinite after intercalation and ball milling is smaller than the one treated only by ball 174

milling, but also less agglomerates and higher lamellarity than treatment only by ball 175

milling. In the rubber industry, kaolinite with high lamellarity is principally used as 176

reinforcing fillers and processing aids. It reduces the diffusion rate of gases and liquids in 177

vulcanised rubber. This is due to their platy morphology, which increases the diffusion 178

path [30]. 179

As a consequence of this delamination/exfoliation, the platelets look less elongated 180

and show the typical euhedral, hexagonal morphology. Although the form of the 181

individual particles has been strongly modified, the layered morphology is preserved and 182

the particle size reduction is very clearly after intercalation and ball milling. The platelets 183

of kaolinite after intercalation and delamination have high aspect. 184

185

3.3 Specific surface area measurements 186

The reduction in the particle size is clearly evident in the SEM (Fig.2) and Table 1. 187

The particle distribution of the original kaolinite is about 45 m. The decrease of particle 188

size obtained under the experimental condition of treatment that kaolinite without 189

intercalation ball milled is lower. The particle size of kaolinte by intercalation decreased 190

to less than 2 m with 39 %. After ball milling, the kaolinite by intercalation were 191

delaminated, and the particle size of the lamellar was reduced to less than 2 m with 192

98%. 193

Table 1 includes the particle size (PS) and specific surface area (SSA) for original 194

kaolinite, intercalation kaolinite, ball-milled kaolinite without intercalation and 195

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ball-milled kaolinite after intercalation. The original kaolinite has a value that is 8.78 196

m2/g. After intercalation the SSA is 12.57 m2/g. The SSA increase to 27.52 m2/g after 197

intercalation and ball-milled. The value of kaolinite SSA after ball-milled without 198

interclation increase is less than that intercalation and ball-milling. 199

200

3.4 FTIR analysis 201

The FTIR spectra of kaolinite and its exfoliations show four important 202

OH-stretching bands at (ν1) 3695, (ν2) 3668, (ν3) 3650 and (ν5) 3620 cm-1, which can be 203

observed in Fig.3. The band (ν1) at 3695 cm-1 is assigned to the in-phase hydroxyl 204

stretching vibration of the inner surface hydroxyl; the bands at 3650 and 3668 cm-1 are 205

assigned to the out-of--phase hydroxyl stretching vibration of the inner surface hydroxyls 206

The outer hydroxyl units are situated on the surface of the lamellae, which are accessible 207

for hydrogen bonding with the appropriate intercalating molecules. The band at (ν5) 3620 208

cm-1 is attributed to the stretching frequency of the internal (inner) hydroxyl groups of 209

kaolinite, which lie within the lamellae in the plane common to both the tetrahedral and 210

octahedral sheets. Being within the layers, the inner hydroxyl cannot participate in 211

hydrogen-bonding to adsorbed molecules. So, the inner hydroxyl stretching band is not 212

usually influenced by the interlayer modification of kaolinite [31-33]. 213

214

The results of the band component analysis of the infrared spectra are reported in 215

Table 2. The decrease in the intensity of both (ν2) 3668 cm-1 and (ν3) 3650 cm-1 bands is 216

illustrated in Fig.3. There is an apparent exponential decrease in the intensity of the 217

hydroxyl stretching bands for the ball milled kaolinite without intercalation, whereas the 218

12

intensity almost has no change after intercalation and delamination. This can be related to 219

the loss of some OH groups though a mechanical grinding, which occurred in the newly 220

external surface generated in the particle size reduction process [5]. The decreasing 221

intensity and the broadening of the OH stretching bands indicate structural deterioration 222

caused by grinding without intercalation. 223

Figure 3 The FTIR spectra in 3750-3550 cm-1 region

of (a) kaolinite, (b) kaolinite ball-milling without

intercalation and (c) kaolinite ball-milling after

intercalation

Fig. 4 the FTIR spectra in 600-1200 cm-1 region of (a)

kaolinite, (b) kaolinite ball-milling without intercalation

and (c) kaolinite ball-milling after intercalation

224

According to Farmer[34] and Franco[3], delamination can be examined from the 225

intensity and position of the Si-O vibrational bands which gives a dipole oscillation 226

perpendicular to the plates. Fig. 4 shows in the 1200-600 cm-1 region, the FTIR spectra of 227

original kaolinite, kaolinite ball milling without intercalation and kaolinite delamination 228

after intercalation. New and low intensity bands appear at low wavenumbers. The bands 229

at (ν10) 1115 cm-1 and (ν15) 940 cm-1 are attributed to the hydroxyl deformation of the 230

inner surface and the Si-O out of plane vibrations. The lack of these two bands and 231

13

decreasing intensity of bands (ν11) 1099 cm-1 and (ν16) 926 cm-1 are also an indication that 232

the damage to structure of kaolinite happened after ball milling without intercalation. 233

After intercalation with KAc solution, these changes are not observed. This is also an 234

indication that there was less damage to the structure of kaolinite in delamination after 235

intercalation, consistent with the results of XRD and SEM. 236

237

4. Conclusions 238

Delamination of kaolinite was achieved through intercalation and ball-milling. The 239

changes in the molecular structure of kaolinite were confirmed by XRD, SEM and FT-IR. 240

The proportion of the particles (<2 μm) increases sharply by intercalation and ball milling, 241

and at the same time the proportion of particles (<1μm) is progressively increased. As a 242

consequence of this particle-size reduction, the SSA increases from 8 to 27 m2/g after 243

intercalation and ball milling. Moreover, no evidence of change of the structural order of 244

kaolinite has been detected from the XRD and FTIR studies. The platelets of kaolinite 245

after intercalation and delamination have higher diameter-thickness ratio and ideal 246

layered morphology. 247

248

Acknowledgment 249

The authors gratefully acknowledge the financial support provided by the National “863” project of 250

China (2008AA06Z109) and the reviewers for their valuable comments that improved the manuscript. 251

252

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References 253

[1] W.N. Martens, R.L. Frost, J. Kristof, E. Horvath, J. Phys. Chem. B 106 (2002) 4162. 254 [2] R.L. Frost, E. Mako, J. Kristof, J.T. Kloprogge, Spectrochimica Acta A 58 (2002) 2849. 255 [3] F. Franco, L.A. Pérez-Maqueda, J.L. Pérez-Rodríguez, J. Colloid Interface Sci. 274 (2004) 107. 256 [4] X. Zhang, D. Fan, Z. Xu, Journal of Tongji University (Natural Science) 33 (2005) 1646. 257 [5] F. Franco, J.A. Cecila, L.A. Pérez-Maqueda, J.L. Pérez-Rodríguez, C.S.F. Gomes, Appl. Clay Sci. 35 258 (2007) 119. 259 [6] E. Mako, J. Kristof, E. Horvath, V. Vagvolgyi, J. Colloid Interface Sci. 330 (2009) 367. 260 [7] H.H. Murray, Appl. Clay Sci. 17 (2000) 207. 261 [8] C. Nkoumbou, A. Njoya, D. Njoya, C. Grosbois, D. Njopwouo, J. Yvon, F. Martin, Appl. Clay Sci. 43 262 (2009) 118. 263 [9] S. Pavlidou, C.D. Papaspyrides, Progress in Polymer Science 33 (2008) 1119. 264 [10] R.L. Frost, E. Mako, J. Kristof, E. Horvath, J.T. Kloprogge, Langmuir 17 (2001) 4731. 265

[11] M. Valášková, M. Rieder, V. Matejka, P. Capkov, A. Slíva, Appl. Clay Sci. 35 (2007) 108. 266 [12] H.A. Essawy, A.M. Youssef, A.A. Abd El-Hakim, A.M. Rabie, Polymer-Plastics Technology and 267 Engineering 48 (2009) 177. 268 [13] W. Koji, The American Mineralogist 46 (1961) 78. 269 [14] R.L. Frost, J. Kristof, T.H. Tran, Clay Miner. 33 (1998) 605. 270 [15] R.L. Frost, J. Kristof, G.N. Paroz, T.H. Tran, J.T. Kloprogge, J. Colloid Interface Sci. 204 (1998) 227. 271 [16] F. Franco, M.D. Ruiz Cruz, Clay Miner. 39 (2004) 193. 272 [17] J.E.F.C. Gardolinski, G. Lagaly, Clay Miner. 40 (2005) 547. 273 [18] R.L. Frost, E. Mako, J. Kristof, E. Horvath, J.T. Kloprogge, J. Colloid Interface Sci. 239 (2001) 458. 274 [19] É. Kristóf, A.Z. Juhász, I. Vassányi, Clay. Clay Miner. 41 (1993) 608. 275 [20] F. Franco, L.A. Pérez-Maqueda, J.L. Pérez-Rodriguez, Thermochim. Acta 404 (2003) 71. 276 [21] R.L. Frost, E. Horváth, É. Makó, J. Kristóf, T. Cseh, J. Colloid Interface Sci. 265 (2003) 386. 277 [22] G. Suraj, C.S.P. Iyer, S. Rugmini, M. Lalithambika, Appl. Clay Sci. 12 (1997) 111. 278 [23] S. Ding, H. Song, Q. Liu, World Journal of Engineering 3 (2006) 86. 279 [24] R.L. Frost, J. Kristof, E. Mako, E. Horvath, Spectrochimica Acta A. 59 (2003) 1183. 280 [25] R.L. Frost, J. Kristof, E. Mako, W.N. Martens, Langmuir 18 (2002) 6491. 281 [26] D.N. Hinckley, Clay. Clay Miner. 11 (1963) 229. 282 [27] R.L. Frost, J. Kristof, G.N. Paroz, J.T. Kloprogge, J. Phys. Chem. B 102 (1998) 8519. 283 [28] K. Tsunematsu, H. Tateyama, J. Am. Ceram. Soc. 82 (1999) 1589. 284 [29] S. Ding, M. Wang, H. Song, B. Xu, Hebei Gongcheng Daxue Xuebao, Ziran Kexueban 25 (2008) 58. 285 [30] Q. Liu, Y. Zhang, H. Xu, Appl. Clay Sci. 42 (2008) 232. 286 [31] T.A. Elbokl, C. Detellier, J. Colloid Interface Sci. 323 (2008) 338. 287 [32] R.L. Frost, Clay. Clay Miner. 46 (1998) 280. 288 [33] R.L. Frost, J. Kristof, E. Horvath, J.T. Kloprogge, J. Colloid Interface Sci. 214 (1999) 109. 289 [34] V.C. Farmer, J.D. Russell, Spectrochim. Acta 22 (1966) 399. 290

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LIST OF TABLES 291

292

Table 1 Hinckley index, particle size and specific surface area data of original kaolin, 293

intercalation kaolin, exfoliation kaolin after intercalation and without intercalation. 294

295

Table 2 Band component analysis kaolin, exfoliated kaolin without intercalation and 296

exfoliated kaolin intercalated by KAc 297

16

Table 1 Hinckley index, particle size and specific surface area data of original 298

kaolinite, intercalation kaolinite, exfoliation kaolinite after intercalation and without 299

intercalation. 300

Kaolinite samples Hinckley Index

PS (<1μm)

PS (<2μm)

SSA(m2/g)

Original kaolinite 1.305 5% 18% 8.78 Intercalation kaolinite 1.297 12% 39% 12.57 Ball milling kaolinite without intercalation

0.852 15% 57% 13.54

Ball milling kaolinite after intercalation

1.225 75% 98% 27.52

301

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Table 2 Band component analysis kaolinite, exfoliated kaolinite without 302

intercalation and exfoliated kaolinite intercalated by KAc 303

304

Band parameters

Original kaolinite Exfoliated kaolinite without intercalation

Exfoliated kaolinite intercalated by KAc

Center FWHM % Center FWHM % Center FWHM % ν1 3694 21.8 6.79 3695 20.0 6.58 3695 23.0 7.18 ν2 3668 15.8 1.18 3669 15.8 0.50 3668 19.5 1.25 ν3 3651 20.6 2.29 3652 27.6 1.38 3651 23.6 2.14 ν5 3620 8.8 2.36 3620 9.1 2.16 3620 13.1 1.89 ν10 1115 12.0 1.90 1113 24.0 6.59 ν11 1099 45.8 13.86 ν12 1045 38.8 11.11 1083 55.1 10.48 1093 48.3 16.23 ν13 1032 18.8 13.97 1033 29.0 17.12 1033 27.6 19.93 ν14 1009 20.0 12.21 1008 20.3 13.87 1008 18.7 9.21 ν15 940 17.6 3.54 939 19.5 2.26 ν16 926 12.2 1.01 925 11.8 1.00 ν17 913 18.9 5.61 914 19.5 6.27 914 21.9 6.67 ν18 791 21.3 0.72 792 26.8 1.10 792 26.5 1.18 ν19 756 23.1 0.81 756 22.2 0.80 756 23.2 0.91 ν20 695 29.2 2.55 697 26.6 2.52 696 28.3 2.88 ν21 590 35.4 1.40 591 37.3 1.50

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LIST OF FIGURES 305

306

Fig.1 the XRD patterns of (a) original kaolinite, (b) kaolinite intercalated by KAc, (c) 307

kaolin exfoliated after intercalation 308

Fig.2 the SEM images of (a) original kaolinite, (b) kaolinite intercalated by 309

potassium acetate, (c) kaolinite ball milling without intercalation and (d) kaolinite 310

by intercalation and delamination 311

Fig.3 the FTIR spectra in 3750-3550 cm-1 region of (a) kaolinite, (b) kaolinite ball 312

milling without intercalation and (c) kaolinite delamination after intercalation 313

Fig.4 the FTIR spectra in 600-1200 cm-1 region of (a) kaolinite, (b) kaolinite ball 314

milling without intercalation and (c) kaolinite delamination after intercalation 315

316

19

317

Fig 1 the XRD patterns of (a) original kaolinite, (b) kaolinite intercalated by KAc, (c) 318

kaolinite delamination after intercalation 319

320

20

321

Fig 2 the SEM images of (a) original kaolinite, (b) kaolinite intercalated by 322

potassium acetate, (c) kaolinite by ball milling without intercalation and (d) 323

kaolinite by intercalation and delamination 324

21

325

Fig. 3 the FTIR spectra in 3750-3550 cm-1 region of (a) kaolinite, (b) kaolinite ball 326

milling without intercalation and (c) kaolinite delamination after intercalation 327

22

328

Fig. 4 the FTIR spectra in 600-1200 cm-1 region of (a) kaolinite, (b) kaolinite ball 329

milling without intercalation and (c) kaolinite delamination after intercalation 330